Thermionic electron emitter containing thorium carbide,thorium oxide and zirconium carbide

ABSTRACT

AN IMPROVED THERMIONIC ELECTRON EMITTER IS PROVIDED CONTAINING THORIUM CARBIDE, THORIUM OXIDE AND ZIRCONIUM CARBIDE.

United States Patent Oflice 3,706,001 Patented Dec. 12, 1972 3,706,001 THERIVHONIC ELECTRON EMI'ITER CONTAINING THORIUM CARBIDE, THORIUM OXIDE AND ZIRCONIUM CARBIDE Thomas J. Nall, Fern Creek, Ky., assignor to the United States of America as represented by the Secretary of the Army No Drawing. Filed Mar. 15, 1971, Ser. No. 124,608 Int. Cl. H01j1/05, 1/14, 1/38, 19/06 US. Cl. 313-346 DC 2 Claims ABSTRACT OF THE DISCLOSURE An improved thermionic electron emitter is provided containing thorium carbide, thorium oxide and zirconium carbide.

This invention relates in general to an improved thermionic emitter and in particular to an improved thermionic emitter containing thorium carbide, thorium oxide and zirconium carbide.

BACKGROUND OF THE INVENTION Thermionic electron emitters such as thorium carbide and thorium carbide-tungsten carbide emitters are known in the art. The difiiculty with these emitters is their inability to emit the high current densities required in certain device applications such as high power microwave tubes, lasers, etc. over a useful operating life.

SUMMARY OF THE INVENTION The general object of this invention is to provide an improved thermionic electron emitter. A particular object of this invention is to provide such an emitter that is capable of supplying, for an extended period of time, a stream of electrons suflicient to produce a rate of emission equal to or greater than thirty amperes per square centimeter of emitting area over a useful operating life of fifty hours.

The aforementioned objects have now been attained by providing a thermionic electron emitter containing thorium carbide (ThC thorium oxide (ThO and zirconium carbide (ZrC). The compounds may be present in the following ranges of percent or 69.7 to 92.6 weight percent:

ThC to atomic percent, Th0 5 to 30 atomic percent or 5.3 to 29.7 weight percent, and ZrC: 1.5 to 5.0 atomic percent or 0.6 to 2.08 weight percent.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 79.4 atomic percent or 80.04 weight percent thorium carbide, 18.1 atomic percent or 1.03 weight percent thorium oxide, and 2.5 atomic percent or 1.03 weight percent zirconium carbide are ground and blended together in a suitable container such as an alumina mortar and pestle to form a homogeneous mixture. The mixing is done in a dry box or a hood to contain the powders. A suitable amount of the powder is then compacted into the desired configuration. The emission mix is then fired in a vacuum of about 10- Torr while under a mechanical pressure of from 600-1500 pounds per square inch. The resulting cathode exhibits seventy six and one-half hours of operating life while maintaining a level of emission in excess of 30 amperes per square centimeter.

We wish it to be understood that we do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person References Cited UNITED STATES PATENTS 2,647,216 7/1953 Brown 313-346 DC 3,134,924 5/ 1964 I-Ienderson et al. 313-346 R DAVID SCHONBERG, Primary Examiner T. H. KUSMER, Assistant Examiner US. Cl. X.R. 313311 

